2.5 tdi fuel system

[oh_superb]

OK, so I have one of those, but wondered if someone could furnish me with more information on the system.

Mine is an AYM engined car, so it has a pump in the fuel tank which presumably only works only when the engine is turning.

What fuel pressure can I expect to see going into the fuel filter?

If BDG engines do not have an in tank pump, then the VP44 will always be pulling fuel into the IP under depression - surely this is bad for the pump, and any restriction in the fuel filter will increase cavitation tendencies, much more so than if fuel is being fed to the pump by the in-tank pump.

Furthermore, the Tee on the fuel filter, presumably this has a thermostat in it and will be recirculating the fuel and not sending it back to the tank while the fuel is cold, right?

There are many cases of VP37 and VP44 pumps having an issue whereby the regulating valve gets stuck open when the inlet side of the IP is subjected to high depression.  Has anyone come across this in a Superb?

Apparently when this valve gets stuck open, the pump is on a downward self-destruct mode.

On our version, it sits on the top of the pump, the intake cross member needs removing for access, and I plan to check it.

Anyone done it?

Furthermore, do these injectors have a tendency to pop at lower pressures as they age? What is the realistic life span between overhauls?  If one or two injectors are popping at low pressure, then this has the IP over as it then struggles to built up pressure on cranking, so the others are not getting fuel.  I was thinking some of my cold start issues might be related to this.

A diesel specialist offered to test my injectors for GBP 12 each.  Subsequent corrections would be extra, re-nozzling I think they said GBP55+VAT each.

Can anyone supply the bosch p/n for an aym engine standard nozzle?  The market is flooded with big nozzles, but all I need is standard.